Show simple item record Foreman, JV Everitt, HO Yang, J McNicholas, T Liu, J 2011-04-15T16:46:13Z 2010-03-15
dc.identifier.citation Physical Review B - Condensed Matter and Materials Physics, 2010, 81 (11)
dc.identifier.issn 1098-0121
dc.description.abstract Ultrafast time-resolved photoluminescence spectroscopy following one- and two-photon excitations of ZnO powder is used to gain unprecedented insight into the surprisingly high external quantum efficiency of its "green" defect emission band. The role of exciton diffusion, the effects of reabsorption, and the spatial distributions of radiative and nonradiative traps are comparatively elucidated for the ultraviolet excitonic and "green" defect emission bands in both unannealed nanometer-sized ZnO powders and annealed micrometer-sized ZnO:Zn powders. We find that the primary mechanism limiting quantum efficiency is surface recombination because of the high density of nonradiative surface traps in these powders. It is found that unannealed ZnO has a high density of bulk nonradiative traps as well, but the annealing process reduces the density of these bulk traps while simultaneously creating a high density of green-emitting defects near the particle surface. The data are discussed in the context of a simple rate equation model that accounts for the quantum efficiencies of both emission bands. The results indicate how defect engineering could improve the efficiency of ultraviolet-excited ZnO:Zn-based white light phosphors. © 2010 The American Physical Society.
dc.language.iso en_US en_US
dc.relation.ispartof Physical Review B - Condensed Matter and Materials Physics
dc.relation.isversionof 10.1103/PhysRevB.81.115318
dc.title Effects of reabsorption and spatial trap distributions on the radiative quantum efficiencies of ZnO
dc.type Journal Article
dc.description.version Version of Record en_US 2010-3-0 en_US
duke.description.endpage 115318 en_US
duke.description.issue 11 en_US
duke.description.startpage 115318 en_US
duke.description.volume 81 en_US
dc.relation.journal Physical Review B en_US
pubs.issue 11
pubs.organisational-group /Duke
pubs.organisational-group /Duke/Trinity College of Arts & Sciences
pubs.organisational-group /Duke/Trinity College of Arts & Sciences/Chemistry
pubs.organisational-group /Duke/Trinity College of Arts & Sciences/Physics
pubs.publication-status Published
pubs.volume 81
dc.identifier.eissn 1550-235X

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